opam usage

I had a program (called wander) that compiled nicely using a copy of 
glMLite that I had compiled myself from source.

But now that I've found opam, i decided to get glMLite through opam 
instead.

I hid the existing library by movingn it away from /usr/lib/ocaml/glMLite,
and then did
	opam instell glMLite
The istallation seemed to go smoothly.

But now when I try to compile wander, using the same old command line,
I get
hendrik@notlookedfor:~/dv/fun/wander$ make wander
ocamlopt -I +glMLite GL.cmxa Glu.cmxa Glut.cmxa jpeg_loader.cmxa 
png_loader.cmxa svg_loader.cmxa genimg_loader.cmxa unix.cmxa wander.ml -o 
wander
File "wander.ml", line 1, characters 0-7:
Error: Unbound module GL
make: *** [wander] Error 2
hendrik@notlookedfor:~/dv/fun/wander$ 

Evidently ocamlopt doesn't know how to find the newly installed library, 
which (I checked) is indeed present in 
	/home/hendrik/.opam/system/lib/glMLite

Evidently something has to change.  What?

-- hendrik